Electronic component, in particular current sensor

ABSTRACT

The invention relates to an electronic component ( 1 ), in particular a current sensor, having a resistance element ( 5 ) made of a resistance material, a first connection part ( 3 ) made of a conductor material for introducing an electrical current into the resistance element ( 5 ), and a second connection part ( 4 ) made of a conductor material for discharging the electrical current from the resistance element ( 5 ). According to the invention, the component ( 1 ) has a temperature-measuring device ( 8 ) for measuring a temperature difference between the resistance element ( 5 ), on the one hand, and at least one of the two connection parts ( 3, 4 ), on the other hand, in order to derive the current from the temperature difference.

BACKGROUND OF THE INVENTION

The invention refers to an electronic component, in particular a currentsensor.

These types of current-sense resistors are known, for example from EP 0605 800 A1 and EP 1 253 430 A1, and allow measurement of an electricalcurrent according to the four-wire technology. In this case, theelectrical current to be measured is passed via two contacts through thecurrent-sense resistor while the electrical voltage is measured via twofurther contacts, which drops over the resistance element of thecurrent-sense resistor. From the voltage measured it is then possible,by applying Ohm's law, to calculate the electrical current which flowsthrough the current-sense resistor.

From EP 1 253 430 A1 it is furthermore known that a measurement valuerecording system in the form of an ASIC (ASIC: Application SpecificIntegrated Circuit) is directly arranged on a current-sense resistor sothat the current-sense resistor forms a current sense module togetherwith the ASIC. Current measurement using this type of current sensemodules offers the advantage of very precise measurement and a lowconstruction size; however, such current sense modules are expensive andare therefore only used for precision applications where a highprecision of measurement is important.

In the industrial area there are numerous applications (for examplecurrent limit switches, electronic fuses, and others), for which it isonly necessary to have a monitoring function in place, whereas theprecision of measurement is less important. For some applications it iseven desirable that the current measurement only reacts slowly tochanges in the current to be measured in order to avoid excessivelyfrequent switching off due to short-term current peaks. It can thereforebe desirable that the current measurement reacts to a change in thecurrent to be measured according to a time constant which is in therange of seconds. Furthermore, it should also be possible to measureboth a direct current and an alternating current, such as a 50 Hertzalternating current, an alternating current strongly distorted byswitching operations, or even a high-frequency alternating current.

Reference is also made to U.S. Pat. No. 3,026,363 concerning the priorart. This patent discloses a component for measurement of the temporalaverage of an electrical signal, such as a broadband signal. Here thereis indeed a temperature measurement made by means of a thermoelement butthe temperature difference between the resistance element and itsconnection parts is not measured.

Furthermore, a current-sense resistor is known from DE 10 2004 062 655A1 for which the heating up of the current-sense resistor and theresultant change in the resistance value is taken into account in orderto avoid temperature-dependent measurement errors. In this regard too,however, the temperature difference between the resistance element andits connection parts is not measured. This patent application thereforejust discloses temperature compensation for a current-sense resistor.

Finally, regarding the general technical background, one is referred toUS 2004/0227522 A1 and US 2010/0040120 A1.

The object of the invention is therefore to create another option forcurrent measurement which is less costly to produce and also,preferably, avoids the above-mentioned disadvantages.

This object is achieved by a current sensor according to the invention.

SUMMARY OF THE INVENTION

The invention is based on the technical insight that a temperaturedifference arises when operating a current sensor between the resistanceelement made out of a resistance material on the one hand and theneighboring connection parts made out of a conductor material on theother hand. This temperature difference is due to the fact that theresistance material of the resistance element is generally of a higherimpedance than the conductor material of the connection parts so that anappropriately larger thermal power loss occurs in the resistance elementgenerating heat, which is thermally removed through the connectionparts. This temperature difference between the resistance element on theone hand and the connection parts on the other hand, in turn depends onthe size of the electrical current, which flows through the resistanceelement, so that this temperature difference constitutes a measure forthe electrical current.

The invention therefore provides a temperature measuring device, whichmeasures the temperature difference between the resistance element onthe one hand and at least one of the two connection parts on the otherhand in order to derive the electrical current to be measured from this.It is necessary to mention here that the temperature measuring device ismeaningfully galvanically separated from the connection parts and theresistance element.

In a preferred exemplary embodiment of the invention, consisting of thetemperature sensors and the evaluation circuit, the temperaturemeasuring device has at least one thermoelement electrically insulatedfrom a shunt with a hot contact point and a cold contact point, whereinthe hot contact point thermally contacts the resistance element whilethe cold contact point thermally contacts one of the two connectionparts. The thermoelement generates a thermoelectric voltage in anenergized condition of the current sensor according to the SeebeckEffect, wherein the measured thermoelectric voltage constitutes thetemperature difference and, therefore, a measure of the electricalcurrent. Thus the thermoelement has elements, which are preferablyaligned in the current sensor parallel to the direction of the current,so that the hot contact point lies on the resistance element while thecold contact point lies one of the connection parts.

In the preferred exemplary embodiment of the invention, the temperaturemeasuring device has a thermopile with a number of thermoelements whichare electrically connected in series. This offers the advantage thatalso relatively low temperature differences between the resistanceelement on the one hand and the connection parts on the other lead to ametrologically evaluatable thermoelectric voltage, since thethermoelectric voltages from the individual thermoelements add togetherwithin the thermopile.

In this connection, the thermopile is preferably arranged in such a waythat the cold contact points of the thermoelement alternately contactthe first connection part and the second connection part thermally. Itis, however, possible as an alternative, that the cold contact points ofthe thermoelement of the thermopile continuously thermally contact onlythe first connection part or only the second connection part.

The concept of thermal contacting used within the framework of theinvention requires that the respective contact points are attached tothe resistance element or the connection part in such a way that thereis a low heat transfer resistance. For example, this thermal contactingcan occur in such a way that the hot or the cold contact points arefirmly glued onto the resistance element or the connection parts using aheat conductive adhesive. One other option for thermal contacting is tofirmly solder the hot or the cold contact points to the resistanceelement or the connection parts using an electrically insulatingcarrier. However, concerning the thermal contacting of the hot or thecold contact points, the invention is not restricted to the aboveexamples but may also be implemented in another way.

In the preferred exemplary embodiment of the invention there are twothermopiles provided electrically insulated from the shunt, wherein thehot contact points on both thermopiles each thermally contact theresistance element. On the first thermopile the cold contact pointsthermally contact the first connection part, whereas on the secondthermopile the cold contact points thermally contact the secondconnection part. Thus the first thermopile measures the temperaturedifference between the resistance element on the one hand and the firstconnection part on the other hand. The second thermopile, on the otherhand, measures the temperature difference between the resistance elementand the second connection part.

In one variant of this exemplary embodiment both of these thermopilesare connected together on the component to form a series connection andare connected with two common contacts on the component. Therefore, thethermoelectric voltage dropping over both contacts mirrors the sum ofboth temperature differences between the resistance element and bothconnection parts.

In another variant of this exemplary embodiment, both thermopiles are,on the other hand, each connected with two contacts electricallyseparated from each other on the component and also separate from each,in order to measure the thermoelectric voltages of both thermopilesseparately from each other. This is then advantageous if a directcurrent is measured and the conductor material of the connection partsis not thermoelectrically adapted to the resistance material of theresistance element. In this case, an asymmetrical temperaturedistribution arises from the resistance element to both connection partsin the current sensor due to the Peltier Effect. The direction of thecurrent can be derived from the difference of the thermoelectricvoltages of both thermopiles, whereas the absolute value of the sum ofboth thermoelectric voltages constitutes a measure of the size of theelectrical current to be measured.

It was already mentioned above that the hot contact points of thethermoelements thermally contact the resistance element since theresistance element in an energized condition is hotter than theneighboring connection parts due to its larger specific electricalresistance. In this case, the hot contact points of the thermoelementcan lie next to each other in a row, wherein the row of hot contactpoints can run essentially transverse to the direction of the current inthe electronic component.

The temperature inside the resistance element is, however, usually notspatially constant, but instead drops from a so-called “hot spot” in themiddle of the resistance element in the direction of the neighboringconnection parts. Furthermore, the temperature of the resistance elementis also not constant in the lateral direction with reference to thedirection of the current, but drops from the middle of the resistanceelement to the exposed edges. It can therefore be advantageous if thehot contact points are arranged in such a way that they are distributedspatially over the resistance element so that the thermopile measures anaverage value of the temperature of the resistance element, whereby themeasurement can be improved.

Indirect measurement of a current by means of a temperature measurementusually is a relatively slow method of measurement, which can beadvantageous for certain applications in order to avoid unnecessarilyfrequent switching off due to short-term current peaks. Therefore, thetemperature measuring device reacts to a temporal change in theelectrical current and, therefore, also the temperature differenceaccording to a certain first time constant, wherein the first timeconstant is greater than 0.5 s, 1 s, 2 s, 5 s or even 10 s. However,with regard to the time constants for the temperature measuring device,the invention is not restricted to the above-stated example values butcan be also realized with other time constants.

In order to improve the temporal dynamics of the current measurementthere is also the possibility, as part of the invention, that thetemporal change in the measured temperature difference is evaluatedinstead of or in addition to the absolute value of the measuredtemperature difference so that, for example, a statement can already beobtained about the current after just 0.3-0.5 seconds. This evaluationof the temporal change in the measured temperature difference is verysuitable for monitoring for short circuits in an electrical circuit.

It should also be mentioned that the temperature measuring device isconstructionally integrated in the preferred exemplary embodiment intothe electronic component. To do this, the temperature measuring devicecan, for example, have a printed circuit board, which is fastened to theconnection part and/or to the resistance element, wherein the printedcircuit board carries the thermopiles. Alternatively, however, there isalso the possibility that the thermopiles are attached directly onto thesurface of the component, wherein the thermopiles are electricallyseparated from the component.

Furthermore, within the framework of the invention, there is also thepossibility that the temperature measuring device also has an evaluationunit in addition to the thermopile, which determines the electricalcurrent, which flows through the electronic component based on themeasured temperature difference. This evaluation unit can, for example,be realized as an ASIC or in some other way.

In one exemplary embodiment of the invention the electronic componentnot only has a temperature measuring device but also a controllableswitching element, wherein the switching element is connected with thetemperature measuring device and switches depending on the measuredtemperature difference. In the preferred exemplary embodiment of theinvention the switching element disconnects an electrical circuit if themeasured temperature difference shows that the electrical currentflowing through the current sensor has exceeded a prescribed maximumvalue. The switching closes the electrical circuit again if thetemperature difference measured by the temperature measuring device goesbelow a prescribed minimum value. In this case, a switching hysteresiscan be provided in such a way that the maximum value is greater than theminimum value. Resetting of the switching element can also take place byhand, however.

It was already mentioned above that the electrical current flowingthrough the current sensor can also be measured by means of a voltagemeasurement according to the known four-wire technology. In a preferredexemplary embodiment of the invention there is also provision for avoltage measurement unit, which measures the electrical voltage, whichdrops over the resistance element in order to allow for derivation ofthe electrical current. In this way, the current measurement takes placeusing two different measuring principles, namely, on the one hand,measurement of the temperature difference between the resistance elementand the neighboring connection parts and, on the other hand, by means ofa voltage measurement according to the known four-wire technology. Thisoffers the advantage of a redundancy for the current measurement.

The voltage measurement unit for measurement of the voltage, which dropsover the resistance element is preferably constructionally integratedinto the electronic component so that the component together with thevoltage measurement unit and/or the temperature measuring device forms acurrent sense module. To this effect, the voltage measurement unit canhave a printed circuit board, which is fastened to the connection partand/or to the resistance element, wherein the printed circuit board can,for example, have an ASIC as described in patent application EP 1 253430 A1 or in EP 1 363 131 A1 mentioned above. Furthermore, the voltagemeasurement unit has two voltage tapping points, which are connectedelectrically with both connection parts in order to measure the voltage,which drops over the resistance element.

In the preferred exemplary embodiment of the invention, the voltagemeasurement unit on the one side and the temperature measuring device onthe other side are arranged on opposing sides of the electroniccomponent. In this connection the temperature measuring device with thethermopile is preferably arranged on the underside of the currentsensor, that is on the assembly side, on which the current sensor can beattached, according to the surface mounting technology (SMD: SurfaceMounted Device), to a printed circuit board. The voltage measurementunit, on the other hand, is preferably arranged on the upper side of thecurrent sensor, that is on the side opposite the assembly side.

It should also be mentioned that the current measurement is temporallysignificantly more dynamic according to the four-wire technology thanthe current measurement through measurement of the temperaturedifference between the resistance element and the neighboring connectionparts. Thus, the voltage measurement unit reacts according to a certainsecond time constant to a temporal change of the electrical currentflowing through the electronic component, wherein the second timeconstant is smaller than the first time constant of the temperaturemeasuring device. For example, the second time constant of the voltagemeasurement unit can be less than 100 ms, 50 ms, 20 ms or 10 ms.

In an advantageous development of the invention the thermoelectricvoltage generated by the thermopile is not only evaluated as ameasurement parameter but also used for power supply. In anotherdevelopment of the invention there is a power supply unit provided,which supplies the temperature measuring device, the voltage measurementunit, the evaluation unit and/or the controllable switching element withthe electrical power required for operation, wherein the power supplyunit is fed by the thermopile so that no external power supply isneeded. In order to achieve an adequately high supply voltage thethermopile can have more than 20, 50, 100, 200, 500 or even more than1000 thermoelements and make an output voltage of more than 50 mV, 100mV or even more than 200 mV available.

In general terms, the invention also encompasses the general principleof having redundant current measurement using a measurement valuerecording system, wherein the measurement value recording systemmeasures the electrical current flowing through the electronic componentaccording to different physical measuring principles such as a four wiremeasurement of current and voltage, on the one hand, and throughmeasurement of the temperature difference between the resistance elementand the neighboring connection parts on the other hand. This generalprinciple of having redundant current measurement can, however berealized using other measuring principles.

In the preferred exemplary embodiment of the invention the connectionparts and/or the resistance element are plate-shaped, in particular in aplanar or bent form. Alternatively, however, there is also thepossibility that the component is formed using a convex or roundmaterial or one of another shape or is formed from pieces of pipe.Furthermore, the connection parts are preferably welded to theresistance element, in particular by means of electron beam welding. Theindividual current-sense resistors can therefore be cut out of aso-called Tri-Band, wherein the Tri-Band can consist of two outer lyingcopper strips, which are electron beam welded with Manganin® stripslying in the middle. This type of manufacture of the current sensor froma composite material is very inexpensive, as is explained in detail inEP 0 605 800 A1.

It should also be mentioned that the conductor material of theconnection parts has a smaller specific electric resistance than theresistance material of the resistance element. For example, theconductor material of the connection parts can have a specific electricresistance of less than 5·10⁻⁷ Ωm, 2·10⁻⁷ Ωm, 1·10⁻⁷ Ωm, 5·10⁻⁸ Ωm oreven 2·10⁻⁸ Ωm. On the other hand, the resistance material of theresistance element is low-ohmic, in particular with a specificelectrical resistance of less than 50·10⁻⁷ Ωm, 20·10⁻⁷ Ωm, 10·10⁻⁷ Ωm oreven 5·10⁻⁷ Ωm. The resistance material does, however, have a higherimpedance than the conductor material with a specific electricalresistance of more than 10·10⁻⁸ Ωm, 20·10⁻⁸ Ωm, 50·10⁻⁸ Ωm, 10·10⁻⁸ Ωm,10·10⁻⁷ Ωm or 20·10⁻⁷ Ωm.

The resistance material of the resistance element is preferably aresistance alloy, in particular copper-manganese-nickel, in particularCu84Ni4Mn12 (Manganin®), nickel-chromium,nickel-chromium-aluminum-silicone, copper-nickel, nickel-iron,copper-nickel-manganese or copper-nickel.

It should also be mentioned that the resistance material of theresistance element preferably has a high temperature constancyconcerning its specific electrical resistance. For example, the lineartemperature coefficient of the resistance material can be less than1·10⁻³K⁻¹, 0.5·10⁻³K⁻¹, 0.2·10⁻³K⁻¹, 0.1·10⁻³K⁻¹, 0.05·10⁻³K⁻¹ or0.03·10³K⁻¹.

Furthermore, it should also be mentioned that the resistance material ofthe resistance element has a different thermoelectric power in thethermoelectric potential series than the conductor material of theconnection parts so that the measurement using thermoelements generatesa respective thermoelectric voltage.

Furthermore, the resistance material of the resistance element usuallyhas a lower thermal conductivity than the conductor material of theconnection parts, so that the temperature in the connection parts dropsmore slowly outwards than in the resistance element itself. For examplethe thermal conductivity of the resistance material of the resistanceelement can lie in the range of 20 Wm⁻¹K⁻¹ up to 500 Wm⁻¹K⁻¹.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantageous developments of the invention are explained in moredetail below together with the description of the preferred exemplaryembodiments of the invention on the basis of the figures. The figuresshow as follows:

FIG. 1A a cross-sectional view of a current-sense module according tothe invention,

FIG. 1B a bottom view of the current sense module according to FIG. 1Afrom the assembly side,

FIG. 1C the temperature curve in the current sense module according toFIGS. 1A and 1B in the direction of the current,

FIG. 2 a bottom view of a modification to the current sense module fromFIGS. 1A-1C with two separate contactable thermopiles,

FIG. 3 a modification to the current sense module according to FIG. 2with two thermopiles electrically connected in series,

FIG. 4 the thermoelectric voltage curve as a function of the electricalcurrent flowing through the current sense module,

FIG. 5 the speed of change of the output voltage for various electricalcurrents, as well as

FIG. 6 a simplified schematic circuit diagram of a novel current sensemodule.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1A and 1B show a current sense module 1 according to the inventionfor measurement of an electrical current in an electrical circuit, suchas in a motor vehicle on-board electrical system.

The current sense module 1 has a current-sense resistor 2, whichconsists of two plate-shaped connection parts 3, 4 made out of copper ora copper alloy and a plate-shaped resistance element 5 made out ofManganin®, wherein the current-sense resistor 2 is cut out of acomposite material strip (“Tri-Band”), which consists of two copperstrips, which are electron beam welded with Manganin® strips lying inthe middle, which is already known from the patent application EP 0 605800 A1 mentioned above.

A voltage measurement unit 6 is arranged on the upper side of thecurrent sense module 1, which voltage measurement unit essentiallyconsists of a printed circuit board 7 and electronic components (forexample an ASIC) of the printed circuit board 7, wherein the voltagemeasurement unit 6 is connected electrically with both connection parts3, 4 and measures the voltage, which drops over the resistance element5, in order, by applying Ohm's law, to calculate the electrical current,which flows through the current-sense resistor 2. The voltagemeasurement unit 6 can have a conventional form here, as described inthe above-mentioned patent application EP 1 253 430 A1.

On the assembly side of the current sense module 1, which is theunderside, there is, on the other hand, a temperature measuring device 8attached, which has a thermopile 9, wherein the thermopile 9 is arrangedon a printed circuit board 10 and has two contacts 11, 12 at which athermoelectric voltage can be measured, which reflects the temperaturedifference between the resistance element 5 on the one hand and theconnection parts 3, 4 on the other hand. To this effect, the thermopile9 has hot contact points 13 and cold contact points 14, 15, wherein thehot contact points 13 thermally contact the resistance element 5 throughthe printed circuit board 10, whereas the cold contact points 14, 15alternately thermally contact the connection part 3 and the connectionpart 4 through the printed circuit board 10. Therefore, thethermoelectric voltage dropping over the contacts 11, 12 mirrors thetemperature difference between the resistance element 5, on the onehand, and the connection parts 3, 4, on the other, wherein thistemperature difference constitutes a measure of the electrical current,which flows through the current-sense resistor 2.

Thus, FIG. 1C shows the temperature curve in the current-sense resistor2 along the direction of the current. From this, it can be seen that aso-called “hot spot” 16 forms in the resistance element 5 with aparticularly high temperature T, while the temperature T drops in bothdirections towards the connection parts 3, 4. It can furthermore be seenin the drawing that the temperature curve has at the transitions fromthe resistance element 5 to the connection parts 3, 4 two kinks 17, 18in it, which kinks are due to the fact that the conductor material ofthe connection parts 3, 4 has a higher thermal conductivity than theresistance material of the resistance element 5.

One advantageous aspect of the current sense module 1 is the fact thatthe current measurement takes place redundantly, namely, on the onehand, by the voltage measurement unit 6 and, on the other hand, by thetemperature measuring device 8.

FIG. 2 shows a bottom view of a modification of the current sense modulepursuant to the FIGS. 1A-1C such that, to avoid repetition, reference ismade to the above-mentioned description, wherein the same referencenumerals are used for the corresponding details.

A particularity of this exemplary embodiment is that the temperaturemeasuring device 8 has two thermopiles 9.1, 9.2, which are galvanicallyseparated from each other. The thermopile 9.1 measures the temperaturedifference between the resistance element 5 and the connection part 3,while the thermopile 9.2 measures the temperature difference between theresistance element 5 and the connection part 4.

The sum of both of the thermoelectric voltages, which are measured byboth thermopiles 9.1, 9.2, constitutes here a measure of the size of theelectrical current which flows through the current-sense resistor 2.

Furthermore, the Peltier effect causes an asymmetrical temperaturedistribution in the current-sense resistor 2 as can also be seen to someextent from FIG. 1C. Based on a comparison of both thermoelectricvoltages, which are generated by both thermopiles 9.1, 9.2, it is alsopossible to determine the direction of the current.

FIG. 3 shows a modification to the specimen embodiment in FIG. 2, soreference is made to the above description to avoid repetition, wherebythe same numbers are used for corresponding details.

In contrast to the exemplary embodiment according to FIG. 2, boththermopiles 9.1, 9.2 are here electrically connected in series.

FIG. 4 shows an example of the curve for a thermoelectric voltage U as afunction of an electrical current I, which flows through thecurrent-sense resistor 2.

FIG. 5 shows example temporal curves for the change in speed dU/dt ofthe thermoelectric voltage as a function of the time expired after achange in the current.

Finally, FIG. 6 shows a simplified circuit diagram of the current sensemodule pursuant to FIGS. 1A-1C such that, to avoid repetition, referenceis made to the above-mentioned description, wherein the same referencenumerals are used for the corresponding details.

In this circuit diagram, it can also be seen that a differentiator 19 isprovided, which differentiator forms the time derivation Δ{dot over (T)}of the temperature difference ΔT measured by the temperature measuringdevice 8.

Furthermore, there is an evaluation unit 20 provided, which determinesthe electrical current I, which flows through the current-sense resistor2. Here, the evaluation unit 20 takes account, on the one hand, of thetemperature difference ΔT and the time derivation Δ{dot over (T)} of thetemperature difference ΔT and, on the other hand, the electrical voltageU, which drops over the resistance element 5 and which is measured bythe voltage measurement unit 6.

The measurement value of the electrical current I measured in this wayis passed on to a threshold element 21, wherein the threshold element 21actuates a relay 22 or some other kind of switching element. If themeasured electrical current I exceeds a prescribed maximum valueI_(MAX), then the threshold element 21 actuates the relay 22 in such away that the electrical circuit is disconnected in order to avoid anyfurther increase in the current. If the electrical current I then goesbelow a prescribed minimum value I_(MIN), the threshold element 21actuates the relay 22 in such a way that the electrical circuit isclosed again. The threshold element 21, in this case, has a switchinghysteresis in order to prevent excessively frequent switching.

Finally, it should also be mentioned that the current sense module 1 hasa power supply unit 23, which is fed by the thermopile 9 and suppliesthe temperature measuring device 8, the differentiator 19, theevaluation unit 20, the threshold element 21, the relay 22 and thevoltage measurement unit 6 with the electrical power required foroperation, so that the current sense module 1 does not need any externalpower supply.

It should furthermore also be mentioned that there is a galvanicseparation 24 provided between the evaluation unit 20 and the voltagemeasurement unit 6.

The invention is not limited to the preferred exemplary embodimentsdescribed above. Instead, a plurality of variants and modifications arepossible, which likewise make use of the concept of the invention.Furthermore, the invention also claims protection for the features ofthe sub-claims independently of the features of the preceding claims towhich they refer so that, as part of the invention, any number ofcombinations of the features mentioned in the claims or in thedescription are possible.

LIST OF REFERENCE NUMERALS

-   1 Current sense module-   2 Current-sense resistor-   3 Connection part-   4 Connection part-   5 Resistance element-   6 Voltage measurement unit-   7 Printed circuit board-   8 Temperature measuring device-   9 Thermopile-   10 Printed circuit board-   11 Connecting contact-   12 Connecting contact-   13 Hot contact point-   14 Cold contact point-   15 Cold contact point-   16 Hot spot-   17 Kink point of the temperature profile-   18 Kink point of the temperature profile-   19 Differentiator-   20 Evaluation unit-   21 Threshold element-   22 Relay-   23 Power supply unit-   24 Galvanic separation

What is claimed is:
 1. An electronic component, namely a current sensor,comprising: a) a resistance element comprising a resistance material; b)a first connection part comprising a conductor material for leading anelectrical current into the resistance element; c) a second connectionpart comprising a conductor material for leading the electrical currentout of the resistance element, wherein the conductor material of thefirst and second connection parts has a smaller specific electricresistance than the resistance material of the resistance element; andd) a measurement value recording system, which is arranged to measurethe electrical current flowing through the electronic component, d1)wherein the measurement value recording system is constructionallyintegrated into the electronic component, and d2) wherein themeasurement value recording system is arranged to measure the electricalcurrent flowing through the electronic component according to a numberof different physical measuring principles, d3) wherein one of themeasurement principles is a four wire measurement, wherein theelectrical current to be measured is passed over two contacts throughthe resistance element while the electrical voltage is measured via twofurther contacts, which drops over the resistance element, d4) whereinthe measurement value recording system comprises a voltage measurementunit, which measures the electrical voltage which drops over theresistance element, wherein: the voltage measurement unit isconstructionally integrated into the electronic component; the voltagemeasurement unit has a printed circuit board, which is fastened to theconnection parts and/or to the resistance element; and the voltagemeasurement unit has two voltage tapping points, which are connectedelectrically with both connection parts in order to measure the voltage,which drops over the resistance element.
 2. The electronic componentaccording to claim 1, wherein a further one of the measurementprinciples includes a measurement of at least a temperature differencebetween the resistance element on the one hand and one of the first andsecond connection parts on the other.
 3. The electronic componentaccording to claim 2, further comprising a temperature measuring devicearranged for measurement of the temperature difference between theresistance element on the one hand and at least one of the first andsecond connection parts on the other hand.
 4. The electronic componentaccording to claim 3, wherein the temperature measuring device has atleast one thermoelement with a hot contact point and a cold contactpoint, wherein the hot contact point thermally contacts the resistanceelement while the cold contact point thermally contacts one of the firstand second connection parts.
 5. The electronic component according toclaim 4, wherein: a) the temperature measuring device has a thermopilewith multiple thermoelements, which are electrically switched one behindanother; b) each hot contact point of the thermoelements is thermally incontact with the resistance element; and c) cold contact points of thethermoelements are alternately thermally in contact with the firstconnection part and the second connection part.
 6. The electroniccomponent according to claim 4, wherein: a) the temperature measuringdevice has a first thermopile and a second thermopile; b) each hotcontact point of the first thermophile and the second thermopile isthermally in contact with the resistance element; c) each cold contactpoint of the first thermopile is thermally in contact with the firstconnection part; and d) each cold contact point of the second thermopileis thermally in contact with the second connection part.
 7. Theelectronic component according to claim 6, wherein the first and secondthermopiles on the component are switched together to form an electricalseries connection and are electrically connected with two commoncontacts to the component.
 8. The electronic component according toclaim 6, wherein the first and second thermopiles on the component areelectrically separated from each other and electrically separatelyconnected respectively with two contacts in order to measurethermoelectric voltages of both thermopiles separately.
 9. Theelectronic component according to claim 5, wherein hot contact points ofthe thermoelements on the resistance elements lie in a row side-by-side,wherein the row of the hot contact points essentially runs transverse toa direction of the current.
 10. The electronic component according toclaim 5, wherein hot contact points of the thermoelements are arrangedin such a way that they are distributed over the resistance element. 11.The electronic component according to claim 3, wherein the temperaturemeasuring device reacts to a temporal change in the temperaturedifference according to a certain first time constant wherein the firsttime constant is greater than 0.5 s.
 12. The electronic componentaccording to claim 3, wherein the temperature measuring devicedetermines and evaluates a temporal change in the measured temperaturedifference.
 13. The electronic component according to claim 3, whereinthe temperature measuring device is galvanically separated from thefirst and second connection parts and the resistance element.
 14. Theelectronic component according to claim 3, wherein the temperaturemeasuring device is constructionally integrated into the electroniccomponent.
 15. The electronic component according to claim 3, whereinthe temperature measuring device has an evaluation unit, whichdetermines the electrical current or an electrical output based on themeasured temperature difference which flows through the electroniccomponent.
 16. The electronic component according to claim 3, whereinthe temperature measuring device has a printed circuit board, which isfastened to the connection parts and/or to the resistance element. 17.The electronic component according to claim 3, further comprising acontrollable switching element, wherein the switching element isconnected with the temperature measuring device and is switcheddepending on the measured temperature difference.
 18. The electroniccomponent according to claim 17, wherein a) the controllable switchingelement is a relay; b) the switching element is electrically connectedin series with the resistance element; c) the switching element opens ifthe temperature difference measured by the temperature measuring deviceexceeds a prescribed maximum value; d) the switching element closes ifthe temperature difference measured by the temperature measuring devicegoes below a prescribed minimum value; and e) the switching element isconstructionally integrated into the electronic component.
 19. Theelectronic component according to claim 18, wherein: a) the voltagemeasurement unit and the temperature measuring device are arranged onopposing sides of the electronic component; b) the temperature measuringdevice reacts to a temporal change in the temperature differenceaccording to a certain first time constant wherein the first timeconstant is greater than 0.5 s; and c) the voltage measurement unitreacts according to a certain second time constant to a temporal changeof the electrical current flowing through the electronic component,wherein the second time constant is smaller than the first time constantof the temperature measuring device.
 20. The electronic componentaccording to claim 3, wherein a) a power supply unit is provided, whichsupplies the temperature measuring device with the electrical currentrequired for operation; b) the power supply unit is fed by thethermopile; c) the thermopile has more than 20 thermoelements; d) thethermopile in an energized condition of the electronic componentprovides an output voltage of more than 50 mV; and e) the electroniccomponent does not need any external power supply due to the powersupply unit.
 21. The electronic component according to claim 1, wherein:a) at least one of the first and second connection parts and theresistance element are plate-shaped; b) the first and second connectionparts are welded to the resistance element; c) the conductor material ofthe first and second connection parts is copper or a copper alloy; d)the conductor material of the first and second connection parts has aspecific electrical resistance of less than 5·10⁻⁷ Ωm; e) the resistancematerial of the resistance element is a resistance alloy selected fromthe group consisting of copper-manganese-nickel, nickel-chromium,nickel-chromium-aluminum-silicone, copper-nickel, nickel-iron,copper-nickel-manganese and copper-nickel; f) the resistance material ofthe resistance element is low-ohmic; g) the resistance material of theresistance element has a high temperature constancy concerning itsspecific electrical resistance, with a linear temperature coefficient ofless than 1·10⁻³K⁻¹; h) the resistance material of the resistanceelement has a different thermoelectric power in the thermoelectricpotential series than the conductive material of the first and secondconnection parts; i) the resistance material of the resistance elementhas a lower thermal conductivity than the conductor material of thefirst and second connection parts; j) the thermal conductivity of theresistance material of the resistance element is less than 100 Wm⁻¹K⁻¹;k) the thermal conductivity of the conductor material of the connectionparts is greater than 100 Wm⁻¹K⁻¹; and l) the resistance material has ahigher impedance than the conductor material, with a specific electricalresistance of more than 10·10⁻⁸ Ωm.